CN111555375A - Circuit, system and method for inducing current - Google Patents

Circuit, system and method for inducing current Download PDF

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Publication number
CN111555375A
CN111555375A CN202010084639.8A CN202010084639A CN111555375A CN 111555375 A CN111555375 A CN 111555375A CN 202010084639 A CN202010084639 A CN 202010084639A CN 111555375 A CN111555375 A CN 111555375A
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CN
China
Prior art keywords
switching element
battery pack
circuit
battery
current
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Pending
Application number
CN202010084639.8A
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Chinese (zh)
Inventor
乌韦·柯克纳
莱奥·艾彻里德勒
斯特凡诺·德菲利皮斯
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Infineon Technologies Austria AG
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Infineon Technologies Austria AG
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Publication of CN111555375A publication Critical patent/CN111555375A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/63—Control systems
    • H01M10/637—Control systems characterised by the use of reversible temperature-sensitive devices, e.g. NTC, PTC or bimetal devices; characterised by control of the internal current flowing through the cells, e.g. by switching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/24—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries
    • B60L58/27—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries by heating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/615—Heating or keeping warm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/63—Control systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/657—Means for temperature control structurally associated with the cells by electric or electromagnetic means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/66—Heat-exchange relationships between the cells and other systems, e.g. central heating systems or fuel cells
    • H01M10/667—Heat-exchange relationships between the cells and other systems, e.g. central heating systems or fuel cells the system being an electronic component, e.g. a CPU, an inverter or a capacitor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0024—Parallel/serial switching of connection of batteries to charge or load circuit
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00309—Overheat or overtemperature protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/007188—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters
    • H02J7/007192—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/567—Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
    • H02J2310/40—The network being an on-board power network, i.e. within a vehicle
    • H02J2310/48—The network being an on-board power network, i.e. within a vehicle for electric vehicles [EV] or hybrid vehicles [HEV]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/342—The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Abstract

Circuits, systems, and methods for inducing current are disclosed. The circuit may include a switching element. The circuit may be configured to draw current from the first battery pack using the switching element when the switching element is turned on, the first battery pack emitting an overcurrent after the switching element is turned off, wherein the current increases a temperature of the first battery pack. Further, the circuit may be further configured to deliver at least some of the overcurrent to the second battery pack when the switching element is off, wherein the overcurrent charges the second battery pack, and wherein the overcurrent increases the temperature of the second battery pack.

Description

Circuit, system and method for inducing current
Technical Field
The present disclosure relates to a circuit electronic device including a switching element.
Background
The switching element may regulate the flow of current in the circuit. For example, when the switching element is "on", the switching element may conduct current, and when the switching element is "off", the switching element may prevent current from passing. The circuit may include switching elements and other circuit components for determining the magnitude of current and the direction of current flow within the circuit. In some cases, a circuit including a switching element may sense and control current through at least a portion of the battery.
Disclosure of Invention
In general, the present disclosure relates to techniques for circuits including switching elements that can sense current through a battery. In some cases, the battery may be divided into a first battery pack and a second battery pack. In some examples, the first battery pack and the second battery pack are connected in parallel, and the circuit is electrically coupled to each of the first battery pack and the second battery pack. The circuit may transfer energy (e.g., current) between the battery packs such that the current passes through the internal resistance of the first battery pack and the internal resistance of the second battery pack, thereby causing the temperature of the battery packs to increase.
Although in some examples, the circuit transfers energy exclusively from the first battery pack to the second battery pack, in other examples, the circuit may be configured for multi-directional energy transfer. For example, the circuit may be configured to alternate between a first switching mode and a second switching mode using the switching element. During the first switching mode, the circuit may transfer energy from the first battery pack to the second battery pack, and during the second switching mode, the circuit may transfer energy from the second battery pack to the first battery pack.
The techniques of this disclosure may have one or more technical advantages. For example, after storing the battery in an abnormally cold environment (e.g., below 0 degrees celsius), it may be difficult or undesirable to deliver power from the battery to the load. One or more techniques of the present disclosure include sensing a current in a battery such that the current passes through an internal resistance of the battery, thereby causing a temperature increase of the battery. After the temperature of the battery increases to the temperature threshold, the likelihood that the battery will be adversely affected by powering the load may be reduced. Additionally, where the battery includes a first battery pack and a second battery pack, it may be beneficial to transfer energy from the first battery pack to the second battery pack. Such energy transfer may increase the temperature of the battery and improve the energy efficiency of the battery, as the energy drawn from the first battery pack may heat both the first battery pack and the second battery pack while charging the second battery pack.
In some examples, a circuit includes a switching element. The circuit is configured to draw current from the first battery pack using the switching element when the switching element is turned on, the first battery pack emitting an overcurrent after the switching element is turned off, wherein the current increases a temperature of the first battery pack. The circuit is further configured to deliver at least some of the overcurrent to the second battery pack when the switching element is off, wherein the overcurrent charges the second battery pack, and wherein the overcurrent increases a temperature of the second battery pack.
In other examples, a system comprises: a first battery pack including a first positive terminal and a first negative terminal; a second battery pack including a second positive terminal and a second negative terminal, wherein the second battery pack is connected in parallel with the first battery pack; and a circuit. The circuit includes a switching element including a source terminal and a drain terminal, wherein the switching element is connected in parallel with the first battery pack and the second battery pack, wherein the source terminal is electrically connected to the first negative terminal and the drain terminal is electrically connected to the first positive terminal, and when the switching element is turned on, the first positive terminal and the first negative terminal are electrically connected via the switching element.
In other examples, a method comprises: when a switching element of the circuit is turned on, current is drawn from the first battery pack using the switching element, wherein the current increases the temperature of the first battery pack. The method further comprises the following steps: when the switching element is turned off, at least some of the overcurrent is delivered to the second battery pack using the circuit, wherein the overcurrent is issued by the first battery pack, wherein the overcurrent charges the second battery pack, and wherein the overcurrent increases the temperature of the second battery pack.
This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, apparatuses, and methods described in detail in the figures and the following description. Further details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Drawings
Fig. 1 is a block diagram illustrating an exemplary system for heating a first battery pack and a second battery pack in accordance with one or more techniques of the present disclosure;
fig. 2 is a circuit diagram of a system including a first battery pack, a second battery pack, and circuitry according to one or more techniques of the present disclosure;
fig. 3 is a circuit diagram of another system including a first battery pack, a second battery pack, and circuitry according to one or more techniques of the present disclosure;
fig. 4 is a circuit diagram of a system including a first battery pack, a second battery pack, a circuit, and a load according to one or more techniques of the present disclosure;
fig. 5 is a flow diagram illustrating an example technique for heating a first battery pack and a second battery pack with a circuit according to one or more techniques of the present disclosure.
Like reference numerals refer to like elements throughout the specification and drawings.
Detailed Description
In general, techniques of the present disclosure may enable circuitry to perform one or more battery heating processes to increase the temperature of a battery above a temperature threshold before the battery is used to power a load. The circuit may include at least one switching element configured to be activated ("on") and deactivated ("off") during operation of the circuit. The circuit may be configured to draw current from the battery using the at least one switching element. Batteries that may be used as power sources may exhibit characteristics of various circuit components. For example, the battery may be composed of a physical structure, and the physical structure may function as a resistor. When current passes through the physical structure of the battery, the resistance characteristics of the physical structure may cause the battery to release heat, thereby increasing the temperature of the battery. These resistance characteristics may be referred to herein as "internal resistance". In practice, each conductive material is defined by an internal resistance. Due to internal resistance, energy is released in the form of heat when an electric current is passed through the conductive material. This phenomenon is known as the joule effect.
During one or more battery heating processes, it may be beneficial to flow current through the battery resulting in an increase in battery temperature. Additionally, it may be beneficial to conserve the charge level of the battery during one or more battery heating processes. For example, a battery may include two or more battery packs connected in parallel. Each battery pack may include a plurality of batteries connected in series, the plurality of batteries defining a power source capable of outputting a current. Each of the battery packs may define an internal resistance. In this way, each of the battery packs may be heated according to the joule effect. In some examples, a circuit of the present disclosure is electrically connected to a first battery pack and a second battery pack, the circuit inducing a current in the first battery pack and delivering the current to the second battery pack. The circuit may pass current through both battery packs and conserve power by transferring energy from the first battery pack to the second battery pack. In some examples described herein, while the circuit transfers energy from the first battery pack to the second battery pack, the circuit may cause the temperature of the first battery pack to increase faster than the circuit causes the temperature of the second battery pack to increase.
To balance the temperature of the first battery pack with the temperature of the second battery pack, the circuit of the present disclosure may be configured to operate in a first switching mode and a second switching mode. The circuit may activate and deactivate the plurality of switching elements to alternate between a first switching mode and a second switching mode. During the first switching mode, the circuit may transfer energy from the first battery pack to the second battery pack and cause the temperature of the first battery pack to increase faster than the temperature of the second battery pack. During the second switching mode, the circuit may transfer energy from the second battery pack to the first battery pack and cause the temperature of the first battery pack to increase faster than the temperature of the second battery pack.
The circuit of the present disclosure may be configured to connect and disconnect the first battery pack and the second battery pack from the load. For example, the circuit may comprise a first load connection switching element and a second load connection switching element. The circuit may deliver current from the first battery pack to the load if the first load connection switching element is activated. Additionally, if the second load connection switching element is activated, the circuit may deliver current from the second battery pack to the load. Deactivating the first load connection switching element disconnects the first battery pack from the load. Deactivating the second load connection switching element disconnects the second battery pack from the load.
Fig. 1 is a block diagram illustrating an example system 100 for heating a first battery stack 110 and a second battery stack 120 in accordance with one or more techniques of the present disclosure. As shown in the example of fig. 1, system 100 includes a first battery pack 110, a second battery pack 120, a circuit 130, a switching element 132, a control circuit 140, a sensor 142, and a load 150.
The batteries may include a first battery pack 110 and a second battery pack 120 (collectively "battery packs 110, 120"), wherein battery packs 110, 120 are configured to provide power to a load 150. In addition to providing power to the load 150, the battery packs 110, 120 may provide power to the circuit 130 and the control circuit 140. In some examples, the batteries exclusively include battery packs 110, 120. Alternatively, in some examples, the battery may include additional battery packs (not shown in fig. 1) in addition to battery packs 110, 120. First battery stack 110 and second battery stack 120 are connected in parallel. As such, both battery packs 110, 120 are configured to provide power to load 150. For example, the battery packs 110, 120 may each include a plurality of cells arranged in series. In some examples, the plurality of batteries includes a plurality of lithium ion batteries. In other examples, the plurality of cells include lead-acid batteries, nickel-metal hydride batteries, or other materials. In some examples, the maximum voltage output of first battery stack 110 is about 400V and the maximum voltage output of second battery stack 120 is about 400V. Since first battery stack 110 and second battery stack 120 are connected in parallel, the total maximum voltage output of battery stacks 110, 120 is about 400V. However, in other examples, the maximum voltage output of each battery pack 110, 120 may be another value or range of values.
The battery packs 110, 120 may each include a positive terminal and a negative terminal. The direction in which current flows between the positive and negative terminals may determine whether the battery packs 110, 120 are being recharged or consumed. For example, if current is sourced from the positive terminal of first battery stack 110 (e.g., current flows from the negative terminal through first battery stack 110 to the positive terminal), first battery stack 110 may consume power. Alternatively, first battery pack 110 may be recharged if current is received at the positive terminal of first battery pack 110 (e.g., current flows from the positive terminal through first battery pack 110 to the negative terminal).
Each of the battery packs 110, 120 includes an internal resistance (not shown in fig. 1) and an internal inductance (not shown in fig. 1). Even though a battery may not be considered a "resistor" or an "inductor," the battery may still exhibit resistive and inductive characteristics when used in a circuit. The battery may include a physical structure. When current passes through the physical structure of the battery, the characteristics of the physical structure may cause internal resistance and internal inductance of the battery. For example, when current passes through first battery stack 110, the physical structure of first battery stack 110 may resist the flow of current through first battery stack 110, thereby representing the internal resistance of first battery stack 110. Also, the physical structure of first battery pack 110 may resist a change in the magnitude of current flowing through first battery pack 110, thereby representing the internal inductance of first battery pack 110. Each of the battery packs 110, 120 is indivisible to its respective internal resistance and internal inductance, and when the battery packs 110, 120 are electrically coupled to the circuit 130, the internal resistance of the battery packs 110, 120 may affect the operation of the circuit 130. When current passes through the internal resistance of the battery pack 110, 120 (e.g., current passes through the respective physical structure of the battery pack 110, 120), the internal resistance releases energy in the form of heat.
The circuit 130 may include circuit elements including any combination of capacitors, resistors, inductors, semiconductors, and transistors. In some examples, the circuit 130, which is controlled by the control circuit 140 in the example of fig. 1, determines the flow of current through the battery packs 110, 120. Circuit 130, placed in parallel between battery packs 110, 120, is configured to determine the interaction between first battery pack 110 and second battery pack 120, and circuit 130 is additionally configured to determine the amount of power delivered from battery packs 110, 120 to load 150. In some examples, control circuitry 140 controls circuitry 130 to perform a battery warm-up process. When battery packs 110, 120 are not being used to power load 150, the battery warm-up process may increase the temperature of first battery pack 110 and increase the temperature of second battery pack 120. Additionally or alternatively, the circuit 130 may act as a gateway between the battery packs 110, 120 and the load 150. For example, circuit 130 may be configured to enable any combination of battery packs 110, 120 to power load 150, and circuit 130 may be configured to disconnect any combination of battery packs 110, 120 from load 150. Some example techniques of the present disclosure may use switching elements of circuit 130, such as switching element 132, to perform a battery warm-up process and connect or disconnect battery packs 110, 120 to load 150.
In some cases, the switching element 132 may include a power switch, such as, but not limited to, any type of Field Effect Transistor (FET), including any combination of Metal Oxide Semiconductor Field Effect Transistors (MOSFET), Bipolar Junction Transistors (BJT), Insulated Gate Bipolar Transistors (IGBT), Junction Field Effect Transistors (JFET), High Electron Mobility Transistors (HEMT), or other element controlled using voltage. In addition, the switching element 132 may include an n-type transistor, a p-type transistor, and a power transistor, or any combination thereof. In some examples, the switching element 132 includes a vertical transistor, a lateral transistor, and/or a horizontal transistor. In some examples, the switching element 132 includes other analog devices such as diodes and/or thyristors. In some examples, the switching element 132 may operate as a switch and/or as an analog device. The switching elements 132 may include a single switching element 132 configured to be controlled by the control circuit 140. Alternatively, the switching element 132 may include a plurality of switching elements 132, wherein each switching element of the plurality of switching elements 132 may be independently controlled by the control circuit 140.
In some examples, wherein the one or more switching elements 132 comprises a single switching element 132, the switching element 132 comprises three terminals: two load terminals and one control terminal. For a MOSFET switch, the switching element 132 may comprise a drain terminal, a source terminal and at least one gate terminal, wherein the control terminal is the gate terminal. For a BJT switch, the control terminal may be a base terminal. Based on the voltage at the control terminal, a current may flow between the two load terminals of the switching element 132. Thus, current may flow through the switching element 132 based on a control signal delivered by the control circuit 140 to the control terminal of the switching element 132. In one example, a voltage amplitude of 10V must be applied to the control terminal of switching element 132 in order to "turn on" switching element 132 so that switching element 132 is able to draw current from first battery stack 110 and conduct electricity. In other examples, other voltage magnitudes may be required to activate the switching element 132. Further, when the voltage applied to the control terminal of the switching element 132 is reduced, the switching element 132 may be turned "off". Additionally, in some examples, wherein the one or more switching elements 132 include a plurality of switching elements 132, the control circuit 140 is configured to independently control each of the switching elements 132.
The switching element 132 may include various material compounds, such as silicon, silicon carbide, gallium nitride, or any other combination of one or more semiconductor materials. In some examples, silicon carbide switches may experience lower power losses. The fast switching means may enable the switching element 132 to draw short bursts of current from the battery packs 110, 120. In some examples, the switching device may include a gallium nitride switch, which may have a faster switching speed than other switches, such as a silicon switch or a silicon carbide switch. These higher frequency switching elements may require control signals (e.g., voltage signals delivered from the control circuit 140 to the control terminals of the switching elements 132) that are sent with more precise timing than the lower frequency switching elements.
In some examples, where the one or more switching elements 132 include a single switching element 132 and the circuit 130 is performing a battery warm-up procedure, the circuit 130 may be configured to draw current from the first battery pack 110 using the switching element 132 when the switching element 132 is turned on. In other words, when switching element 132 is turned on, switching element 132 generates a short circuit including first battery stack 110, thereby causing a current to flow through first battery stack 110 and switching element 132. This current may cause the temperature of first battery stack 110 to increase. After the switching element 132 is turned off, the first battery pack 110 issues an overcurrent. In some examples, the overcurrent is emitted by an internal inductance of first battery stack 110 that resists changes in the magnitude of the current through first battery stack 110. When switching element 132 is turned off, circuit 130 may deliver at least some of the overcurrent to second battery stack 120, where the overcurrent charges second battery stack 120, and where the overcurrent increases the temperature of second battery stack 120. The circuit 130 may additionally include a capacitor. In some examples, a capacitor is placed in parallel with the switching element 132. Circuit 130 may be configured to charge the capacitor with the overcurrent issued by first battery stack 110 when switching element 132 is off. Circuit 130 is configured to discharge the capacitor when switching element 132 is turned on, the capacitor sourcing a second current to second battery stack 120. The second current may charge second battery stack 120, and the second current may increase the temperature of second battery stack 120.
In such an example, where one or more switching elements 132 comprise a single switching element, circuitry 130 may be configured to transfer energy from first battery stack 110 to second battery stack 120, while circuitry 130 may not be configured to transfer energy from second battery stack 120 to first battery stack 110. Therefore, during a period of time when the battery warm-up process begins, first battery stack 110 may lose charge and second battery stack 120 may gain charge. Furthermore, the temperature of first battery stack 110 may increase faster than the temperature of second battery stack 120 over a period of time because the magnitude of the current induced in first battery stack 110 when switching element 132 is on is greater than the magnitude of the overcurrent delivered to second battery stack 120 when switching element 132 is off. To correct for this asymmetry in charge and temperature between the battery packs 110, 120 during the battery warm-up process, it may be beneficial in some cases to include multiple switching elements 132 in the circuit 130.
In some examples where the one or more switching elements 132 include a plurality of switching elements 132, the control circuit 140 may be configured to control the plurality of switching elements 132 to alternate between a first switching mode and a second switching mode. In this manner, the control circuit 140 is configured to control the plurality of switching elements 132 to change the direction in which energy is transferred between the battery packs 110, 120. For example, during the first switching mode, first switching element 132 may induce a current in first battery pack 110 when first switching element 132 is turned on. In addition, when the first switching element 132 is turned off, the circuit 130 may deliver an overcurrent to the second battery pack 120. When circuit 130 operates in the second switching mode, second switching element 132 may induce a current in second battery pack 120. Circuit 130 is configured to deliver an overcurrent to first battery pack 110 when the second switching element is off.
During the first switching mode, the charge of first battery stack 110 may decrease and the charge of second battery stack 120 may increase. In addition, the temperature of first battery stack 110 may increase faster than the temperature of second battery stack 120. Alternatively, during the second switching mode, the charge of the first battery stack 110 may increase and the charge of the second battery stack 120 may decrease. In addition, the temperature of second battery stack 120 may increase faster than the temperature of first battery stack 110. In some examples, it may be beneficial for the circuit 130 to alternate between the first switching mode and the second switching mode in order to balance the charge level and temperature of the battery packs 110, 120 during the battery warm-up process.
In some examples, the circuit 130 is configured to operate in a first switching mode during a plurality of primary stages, wherein each primary stage of the plurality of primary stages lasts for a first amount of time. Additionally, the circuit 130 is configured to operate in a second switching mode during a plurality of secondary phases, wherein each secondary phase of the plurality of secondary phases lasts for a second amount of time. The circuit 130 may be configured to interleave a plurality of primary stages and a plurality of secondary stages such that a primary stage is followed by a secondary stage and a secondary stage is followed by a successive primary stage. In this manner, the circuit 130 may balance the temperature and charge level of the battery packs 110, 120.
The control circuitry 140 may include one or more of a microprocessor, a controller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), discrete logic circuitry, or any other processing circuitry configured to provide the functionality attributed to the control circuitry 140 herein. The control circuit 140 may be implemented as firmware, hardware, software, or any combination thereof. In some examples, any combination of first battery stack 110 and second battery stack 120 provides power to control circuit 140. Additionally, or alternatively, the control circuit 140 may be powered by an auxiliary battery or another energy source. In some examples, the control circuit 140 is configured to deliver a control signal to the switching element 132, controlling the flow of current through the switching element 132. The control circuit 140 may adjust the amount of time the switching element 132 is on and adjust the amount of time the switching element 132 is off.
To adjust the amount of time that the switching element 132 is on, the control circuit 140 may deliver a control signal to the control terminal of the switching element 132 to accurately determine the amount of time that the switching element 132 is on. In some examples, at least some of the one or more switching elements 132 are "fast" switching devices that require precise control signals from the control circuit 140 to operate. Additionally, in some examples, at least some of the one or more switching elements 132 may be "slow" switching devices. The control signal for operating the slow switching device is not as accurate as the control signal for operating the fast switching device.
Control circuit 140 includes a sensor 142. The sensor 142 may include a temperature sensor, a voltage sensor, a current sensor, a light sensor, an accelerometer, or any combination thereof. In some examples, it may be beneficial to use the sensor 142 to determine when the circuit 130 alternates between the first switching mode and the second switching mode. In some examples, sensors 142 include a first temperature sensor configured to measure the temperature of first battery stack 110 and a second temperature sensor configured to measure the temperature of second battery stack 120. Control circuit 140 is configured to change circuit 130 from operating in the first switching mode to operating in the second switching mode if the temperature of first battery stack 110 is greater than the temperature of second battery stack 120 by more than a temperature difference threshold. Additionally, control circuit 140 is configured to change circuit 130 from operating in the second switching mode to operating in the first switching mode if the temperature of second battery stack 120 is greater than the temperature of first battery stack 110 by more than a temperature difference threshold. In some examples, the temperature difference threshold is in a range between 1 degree celsius and 5 degrees celsius. However, in other examples, other temperature difference thresholds may be used. The temperature difference threshold may be any temperature value or range of temperature values.
In some examples, sensors 142 include a first voltage sensor configured to measure a magnitude of a voltage of first battery stack 110 and a second voltage sensor configured to measure a magnitude of a voltage of second battery stack 120. Control circuit 140 is configured to change circuit 130 from operating in the first switching mode to operating in the second switching mode if the magnitude of the voltage of first battery stack 110 is less than the magnitude of the voltage of second battery stack 120 by more than the voltage difference threshold. Additionally, control circuit 140 is configured to change circuit 130 from operating in the second switching mode to operating in the first switching mode if the magnitude of the voltage of second battery stack 120 is less than the magnitude of the voltage of first battery stack 110 by more than the voltage difference threshold. In some examples, the voltage difference threshold is in a range between 1 volt and 5 volts. However, in other examples, other voltages may define different thresholds for the voltages. The voltage difference threshold may be any voltage value or range of voltage values.
In some examples, control circuitry 140 may initiate a battery warm-up process based on sensor 142. For example, if sensor 142 detects that the temperature of battery packs 110, 120 is below a temperature threshold, control circuitry 140 may control circuitry 130 to initiate a battery warm-up process. Alternatively, if the sensor 142 detects that the temperature of the battery packs 110, 120 is above a temperature threshold, the control circuit 140 may connect the battery packs 110, 120 to the load 150 without initiating the battery warm-up process. In some examples, the temperature threshold is zero degrees celsius.
The load 150 may define a collection of electrical components that consume electrical power. In some examples, the load 150 may include a brushless direct current (BLDC) motor, a brushed DC (DC) motor, an Alternating Current (AC) induction motor, or other types of motors. Additionally, in some examples, the load 150 includes a collection of circuit components, such as resistors, inductors, capacitors, diodes, and other semiconductor elements. In some examples, the load 150 includes a motor and other electrical components (e.g., an instrument panel, a control panel, a heating/cooling system, and lights) of a Battery Electric Vehicle (BEV) or a Hybrid Electric Vehicle (HEV). Example BEVs and HEVs include automobiles, trucks, buses, motorcycles, golf carts, All Terrain Vehicles (ATVs), snowmobiles, aircraft, and watercraft. In other examples, the load 150 includes motors and electrical components used in other applications.
In some examples, load 150 requires a large current from first battery stack 110 and second battery stack 120. For example, the maximum current required by the load 150 may be greater than about 1000 amps. If the maximum current is drawn from the battery packs 110, 120 when the temperature of the battery packs 110, 120 is below the temperature threshold, the maximum current required by the load 150 may adversely affect the long-term quality of the battery packs 110, 120. Although the battery warm-up process described herein includes drawing current from the battery packs 110, 120, in some examples, the maximum current amplitude drawn from the battery packs 110, 120 by the load 150 is greater than the maximum current amplitude drawn from the battery packs 110, 120 by the switching unit 132. As such, when the battery temperature is below the temperature threshold, it may be preferable to perform the battery warm-up process to increase the temperature of the battery packs 110, 120 rather than to power the load 150.
In some cases, circuit 130 may determine the combination of battery packs 110, 120 connected to load 150 and the combination of battery packs 110, 120 disconnected from load 150. In some examples, the switching element 132 includes a first load connection switch and a second load connection switch. The circuit 130 may connect the load 150 to the battery packs 110, 120 when the first and second load connection switches are turned on. In addition, circuit 130 may disconnect load 150 from first battery pack 110 when the first load connection switch is off, and disconnect load 150 from second battery pack 120 when the second load connection switch is off. In other words, if the first load connection switch is turned on, the load 150 is connected to the first battery pack 110, and if the second load connection switch is turned on, the load 150 is connected to the second battery pack 120.
Fig. 2 is a circuit diagram of a system 200 including a first battery pack 210, a second battery pack 220, and a circuit 230 according to one or more techniques of the present disclosure. The first battery pack 210 includes a first internal inductor 212, a first internal resistor 214, and a first power source 216. The second battery pack 220 includes a second internal inductor 222, a second internal resistor 224, and a second power source 226. The circuit 230 includes a switching element 232, a capacitor 234, and a diode 236. First battery pack 210 may be an example of first battery pack 110 of fig. 1. Second battery pack 220 may be an example of second battery pack 120 of fig. 1. The circuit 230 may be an example of the circuit 130 of fig. 1.
In some examples, first battery pack 210 may include a plurality of batteries placed in series. The plurality of batteries may include lithium ion batteries, lead acid batteries, nickel metal hydride batteries, or any combination thereof. The first battery pack 210 may include a positive terminal and a negative terminal. In some examples, power is dissipated from first battery stack 210 when current is drawn from the negative terminal through first battery stack 210 to the positive terminal. Alternatively, in some examples, the first battery pack 210 is recharged while current flows from the positive terminal through the first battery pack 210 to the negative terminal.
An inductor is a circuit component that resists changes in the magnitude of current through the inductor. In some examples, the inductor is defined by an electrically conductive wire wrapped in a coil. When a current is passed through the coil, a magnetic field is generated in the coil and induces a voltage across the inductor. The inductor defines an inductance value, and the inductance value is the ratio of the voltage across the inductor to the rate of change of the current through the inductor. Although inductors are distinct and identifiable circuit components, other circuit components than inductors may behave in some manner like inductors. For example, capacitors, resistors, batteries, semiconductor elements, and other types of circuit components may define inductance values, even though the inductance may not be the "expected" characteristic of such components.
Although first battery pack 210 may not resemble a physical inductor assembly (e.g., a wire wound in a coil), first battery pack 210 may define a first internal inductance 212. As such, when the first battery pack 210 is connected to the circuit 230, the first battery pack 210 may exhibit at least some characteristics of the physical inductor component. For example, the physical structure of first battery pack 210 may resist changes in the magnitude of current through the physical structure of first battery pack 210. As such, the first internal inductance 212 may not define physical circuit components. Rather, first internal inductance 212 may define an inherent characteristic of first battery pack 210 that is inseparable from the structure of first battery pack 210. The first internal inductance 212 may correspond to a first inductance value, and in one example, the first inductance value is in a range between 1 microhenry and 20 microhenries. Due to the nature of first internal inductance 212, first battery stack 210 may resist changes in the magnitude of the current flowing through first battery stack 210. Therefore, if the drawing circuit connected to first battery pack 210 is turned off, first battery pack 210 may continue to emit an overcurrent for a period of time due to first internal inductance 212 resisting a change in the magnitude of current flowing through first battery pack 210.
Additionally, first battery pack 210 may define a first internal resistance 214. Similar to the first internal inductor 212, the first internal resistor 214 is represented by a separate circuit component. Rather, first internal resistance 214 is an inherent characteristic of first battery pack 210 that is inseparable from the physical structure of first battery pack 210. Similar to a conventional resistor, the physical structure of the first battery pack 210 may resist the current flowing through the first battery pack 210. In this manner, when current flows through the physical structure of first battery stack 210, first battery stack 210 emits heat, and the temperature of first battery stack 210 increases due to the joule effect. In some examples, the first internal resistance 214 may define a resistance value in a range between 1 milliohm (m Ω) and 5 milliohm (m Ω).
In some cases, the internal resistance is referred to as a "parasitic resistance" and the internal inductance is referred to as a "parasitic inductance.
The first battery pack 210 may also define a first power source 216 that gives a voltage output value. A voltage defined as the potential difference between two points can drive a current through the circuit. In the example shown in fig. 2, first power source 216 is a potential difference between the positive and negative terminals of first battery stack 210. In some examples, the first power supply 216 may define a maximum voltage output of 400 volts.
In the example shown in fig. 2, second battery pack 220 includes a second internal inductor 222, a second internal resistor 224, and a second power source 226. In some examples, second battery pack 220 is a duplicate or near-duplicate of first battery pack 110. For example, second battery pack 220 may be composed of the same material as first battery pack 210, second battery pack 220 may be about the same size (e.g., length, width, and volume) as first battery pack 210, and second battery pack 220 may include the same number of cells as first battery pack 210. In other examples, second battery pack 220 may differ from first battery pack 210 in at least one of material composition, size, and number of cells. In some examples, the second power supply 226 may define a maximum voltage output of 400 volts.
First battery stack 210 and second battery stack 220 are connected in parallel. As such, when first battery stack 210 and second battery stack 220 (collectively "battery stacks 210, 220") are connected to a load (e.g., load 150 of fig. 1), the voltage output of first battery stack 210 may be equal or nearly equal to the voltage output of second battery stack 220, according to Kirchhoff's Voltage Law (KVL).
In some cases, it may be undesirable to use the battery packs 210, 220 to power a load when the battery packs 210, 220 are at a particularly cold temperature, such as a temperature below zero degrees celsius. If the battery packs 210, 220 are used to power a load at cryogenic temperatures, the battery packs 210, 220 may consume more energy to cause a chemical reaction that enables the battery packs 210, 220 to output electrical power. Thus, using the battery packs 210, 220 to power a load at cryogenic temperatures may reduce the efficiency of the battery packs 210, 220. Additionally, using the battery packs 210, 220 to power a load when the temperature of the battery packs 210, 220 is below zero degrees celsius may permanently damage the battery packs 210, 220 such that the energy capacity of the battery packs 210, 220 is reduced even when the temperature of the battery packs 210, 220 is above zero degrees celsius.
The circuit 230 may be configured to perform a battery warm-up procedure that increases the temperature of the battery packs 210, 220 until the temperature of the battery packs 210, 220 is high enough for the battery packs 210, 220 to power a load without causing permanent damage to the battery packs 210, 220. For example, the circuit 230 may increase the temperature of the battery packs 210, 220 above a temperature threshold. In some examples, the temperature threshold is zero degrees celsius.
In some cases, switching element 232 comprises a power switch, such as, but not limited to, any type of field effect transistor, including any combination of MOSFETs, BJTs, IGBTs, JFETs, HEMTs, or additional elements controlled using voltage. In addition, the switching element 232 may include an n-type transistor, a p-type transistor, and a power transistor, or any combination thereof. In some examples, the switching element 232 includes a vertical transistor, a lateral transistor, and/or a horizontal transistor. In some examples, the switching element 232 includes other analog devices such as diodes and/or thyristors. In some examples, the switching element 232 may operate as a switch and/or as an analog device.
In some examples, the switching element 232 includes three terminals: two load terminals and a control terminal. For a MOSFET switch, the switching element 232 may comprise a drain terminal, a source terminal and at least one gate terminal, wherein the control terminal is the gate terminal. For a BJT switch, the control terminal may be a base terminal. Based on the voltage at the control terminal, a current may flow between the two load terminals of the switching element 232. Thus, current may flow through the switching element 232 based on a control signal delivered to a control terminal of the switching element 232 by a controller (control circuit 140 of fig. 1). In one example, a voltage amplitude of 10V must be applied to the control terminal of the switching element 232 in order to "turn on" the switching element 232 so that the switching element 232 can conduct. In other examples, other voltage magnitudes may be required to activate the switching element 232. Further, the switching element 232 may be turned "off" when the magnitude of the voltage applied to the control terminal of the switching element 232 is reduced.
The switching element 232 may comprise various material compounds, such as silicon, silicon carbide, gallium nitride, or any other combination of one or more semiconductor materials. In some examples, silicon carbide switches may experience lower power losses. The fast switching device may enable the switching element 232 to draw short bursts of current from the battery (e.g., battery packs 210, 220). In some examples, the fast switching device may include a gallium nitride switch, which may have a faster switching speed than a silicon switch or a silicon carbide switch. These higher frequency switching elements may require control signals that are sent with more precise timing than the lower frequency switching elements. In some examples, the switching element 232 may be a fast switching element. For example, the switching period of the switching element 232 may include an "on" phase lasting more than 1.5 microseconds (μ s) and less than 2.5 μ s, and an "off" phase lasting more than 15 microseconds and less than 30 microseconds. In one example, a drain terminal of the switching element 232 is electrically connected to a positive terminal of the first battery pack 210, and a source terminal of the switching element 232 is electrically connected to a negative terminal of the first battery pack 210.
In some examples, switching element 232 is configured to draw current from first battery stack 210 when switching element 232 is on. For example, a controller (e.g., control circuit 140 of fig. 1) may apply a voltage to a control terminal of switching element 232, enabling switching element 232 to conduct. When switching element 232 is turned on, switching element 232 creates a short circuit between the positive and negative terminals of first battery stack 210, thereby inducing a current across first battery stack 210 and switching element 232. Since the current flows through the physical structure of the first battery pack 210 and, in turn, through the first internal resistance 214, the first battery pack 210 dissipates heat due to the joule effect. Thus, the current induced by the switching element 232 increases the temperature of the first battery pack 210.
When the switching element 232 is turned on, the current flowing through the first battery pack 210 may increase until it reaches the maximum current amplitude. In some examples, the maximum current amplitude is in a range between 50 amps and 500 amps. For example, after the switching element 232 is turned on for a period of 2 μ s, the magnitude of the current flowing through the first battery pack 210 may be 300 amperes. First internal inductance 212 resists variation in the magnitude of the current flowing through first battery stack 210. In this way, when switching element 232 is turned off, first battery pack 210 issues an overcurrent to second battery pack 220 via diode 236. From the time when the switching element 232 is turned off, the overcurrent may be reduced from the maximum overcurrent magnitude. In some examples, the switching element 232 is turned off for a period of time lasting 20 μ s, and the overcurrent is reduced from a maximum overcurrent value of 300 amperes to zero amperes within the period of time. The example current amplitude values and durations described herein are not intended to be limiting. The maximum current amplitude, the maximum overcurrent amplitude, and the duration of the "on" and "off phases of the switching element 232 may be any value or range of values.
In some examples, circuitry 230 may deliver at least some of the overcurrent to second battery pack 220. The circuit 230 may deliver an overcurrent to the positive terminal of the second battery pack 220, which means that the overcurrent flows from the positive terminal through the second battery pack 220 to the negative terminal. In this way, the second battery pack 220 can be charged by the overcurrent. Since the overcurrent flows through the physical structure of second battery pack 220, the overcurrent passes through the physical structure of second battery pack 220 defining second internal resistance 224, thereby causing the temperature of second battery pack 220 to increase due to the joule effect. Additionally, in the example shown in fig. 2, the circuit 230 is configured to deliver at least some of the overcurrent to the capacitor 234.
Capacitor 234 is a circuit component configured to store electrical potential energy. In some examples, the capacitor 234 may be in a "charged" state, wherein the capacitor 234 stores a maximum amount of electrical potential energy. Additionally, the capacitor 234 may be in a "discharged" state, wherein the capacitor 234 stores less or no electrical potential energy. The capacitor 234 may also be switched between a charged state and a discharged state. When the capacitor 234 is charging, current flows through the capacitor 234, thereby increasing the potential energy stored by the capacitor 234. When the capacitor 234 is discharging, the stored potential energy of the capacitor 234 is released, causing the capacitor 234 to emit current.
When the switching element 232 is off, the over current delivered by the circuit 230 to the capacitor 234 may charge the capacitor 234. In some examples, the overcurrent charges the capacitor 234 to full capacity. In other examples, the overcurrent charges the capacitor 234 to less than full capacity. After switching element 232 turns on, capacitor 234 discharges, releasing the second current to second battery pack 220. In some examples, capacitor 234 discharges a second current to the positive terminal of second battery pack 220, which charges second battery pack 220 and increases the temperature of second battery pack 220.
In other words, the circuit 230 may operate in two phases. During the first phase, switching element 232 is turned on, causing a first current to flow through first battery stack 210 and switching element 232, and causing a second current to flow from discharge capacitor 234 through second battery stack 220. During the second phase, switching element 232 is turned off and first battery pack 210 issues an overcurrent that charges capacitor 234 and flows through second battery pack 220. In the example of fig. 2, the magnitude of the first current is greater than the magnitude of the second current. Therefore, the temperature of first battery stack 210 increases faster than the temperature of second battery stack 220. In one example, it takes 18.7 minutes for circuit 230 to increase the temperature of first battery pack 210 by 25 degrees celsius, and it takes 37.6 minutes for circuit 230 to increase the temperature of second battery pack 220 by 25 degrees celsius. In addition, during a certain period of time, second battery pack 220 may be charged and first battery pack 210 may consume power. In this manner, the circuit 230 may operate "asymmetrically" when performing a battery warm-up process, resulting in an imbalance between the temperature of the battery packs 210, 220 and the charge level of the battery packs 210, 220.
Fig. 3 is a circuit diagram of a system 300 including a first battery pack 310, a second battery pack 320, and a circuit 330, according to one or more techniques of the present disclosure. First battery pack 310 includes a first internal inductor 312, a first internal resistor 314, and a first power source 316. The second battery pack 320 includes a second internal inductor 322, a second internal resistor 324, and a second power source 326. The circuit 330 includes switching elements 332A-332D (collectively "switching elements 332"), a capacitor 334, a diode 336, and a diode 338. First battery pack 310 may be an example of first battery pack 110 of fig. 1. Second battery stack 320 may be an example of second battery stack 120 of fig. 1. The circuit 330 may be an example of the circuit 130 of fig. 1.
In the example of fig. 3, the first battery pack 310 and the second battery pack 320 (collectively "battery packs 310, 320") may be the same as or similar to the battery packs 210, 220 of fig. 2. As such, in some examples, the battery packs 310, 320 may each include a plurality of cells arranged in series. The plurality of batteries may include lithium ion batteries, lead acid batteries, nickel metal hydride batteries, or any combination thereof.
In some examples, to use the battery packs 310, 320 to power a load (e.g., the load 150 of fig. 1), it may be beneficial for the temperature of the battery packs 310, 320 to be above a temperature threshold. The circuit 330 may be configured to perform a battery warm-up process that will increase the temperature of the battery packs 310, 320 until the temperature is high enough for the batteries to power the load without causing permanent damage to the battery packs 310, 320. Therefore, it is desirable to heat first battery stack 310 and second battery stack 320 at about the same rate. The battery warm-up process performed by circuitry 330 may balance the rate at which first battery stack 310 and second battery stack 320 heat up. Thus, the battery warm-up process of circuit 330 may generally prevent first battery stack 310 from heating up faster than second battery stack 320, and likewise may generally prevent second battery stack 320 from heating up faster than first battery stack 310. Additionally, in some examples, the battery warm-up process of the circuit 330 may facilitate balancing of energy transfer between the battery packs 310, 320.
In the example of fig. 3, during the battery heating process, the circuitry 330 may balance the charge level and temperature of the battery packs 310, 320 by alternating between the first switching mode and the second switching mode. For example, while operating in the first switching mode, the circuit 330 is configured to charge the second battery pack 320 using the first battery pack 310. While operating in the second switching mode, the circuit 330 is configured to charge the first battery using the second battery pack 320. By alternating between the first switching mode and the second switching mode, the circuit 330 is configured to balance the temperature and charge level of the battery packs 310, 320.
A controller (e.g., control circuit 140 of fig. 1) may control switching element 332 to alternate between a first switching mode and a second switching mode. In some examples, at least one of the switching elements 332 is an example of the switching element 132 of fig. 1. In some examples, switching element 332A and switching element 332B are fast switching devices that require precise control signals from a controller to operate. In some examples, the switching elements 332A and 332B may include any combination of silicon MOSFETs, silicon JFETs, superjunction MOSFETs, gallium nitride HEMTs, gallium nitride MOSFETs, silicon carbide MOSFETs, or silicon carbide JFETs. In some examples, switching elements 332C and 332D are slow switching devices, such as electromechanical-based switching devices (e.g., relays).
When circuit 330 operates in the first switching mode, the controller may be configured to control circuit 330 to charge second battery pack 320 using first battery pack 310. For example, when the circuit 330 is operating in the first switching mode, the controller may operate (e.g., turn on and off) the switching element 332A when the switching element 332B is off, the switching element 332C is off, and the switching element 332D is on. In some examples, circuitry 330 is configured to draw a first current from first battery pack 310 using switching element 332A when switching element 332A is on. For example, when switching element 332A is turned on, switching element 332A creates a short circuit between the positive and negative terminals of first battery stack 310, thereby inducing a current across first battery stack 310 and switching element 332A. As current flows through the physical structure of first battery pack 310 and, in turn, through first internal resistance 314, first battery pack 310 dissipates heat due to the joule effect. Thus, the current induced by switching element 332A increases the temperature of first battery stack 310.
First battery pack 310 is configured to issue a first overcurrent after switching element 332A is turned off, and circuitry 330 is configured to deliver at least some of the first overcurrent to second battery pack 320. Additionally, the circuit 330 may use at least some of the first overcurrent to charge the capacitor 334. The inductive characteristic of first battery pack 310 (e.g., first internal inductance 312) may cause first battery pack 310 to emit a first overcurrent. In the example shown in fig. 3, first battery pack 310 discharges a first overcurrent to the positive terminal of second battery pack 320 through diode 336 and switching element 332D. The first overcurrent flows from the positive terminal to the negative terminal through the second cell stack 320. Since the first overcurrent passes through the second internal resistance 324, the second battery pack 320 may emit heat. Accordingly, the first overcurrent may recharge the second battery pack 320, and the first overcurrent may increase the temperature of the second battery pack 320 due to the joule effect.
In some cases, after the capacitor 334 is charged with the first overcurrent, the switching element 332A is turned on. After switching element 332A is turned on, capacitor 334 is discharged, releasing the second current to second battery pack 320 via switching element 332D.
During the first switching mode, the circuit 330 may operate in two phases. During the first phase, switching element 332A is turned on, so that a first current flows through first battery stack 310 and switching element 332A, and a second current flows from discharge capacitor 334 to second battery stack 320 through switching element 332D. During the second phase, the switching element 332A is turned off and the first battery pack 310 emits the first overcurrent. The circuit 330 may use at least some of the first overcurrent to charge the capacitor 334. In addition, circuit 330 delivers at least some of the first overcurrent to second battery pack 320 via diode 336 and switching element 332D. In some examples, the second current and the first overcurrent flow from the positive terminal to the negative terminal through the second battery pack 320.
In the example of fig. 3, the magnitude of the first current is greater than the magnitude of the second current. In some examples, first internal resistance 314 of first battery stack 310 is equal to or nearly equal to second internal resistance 324 of second battery stack 320. Therefore, the temperature of first battery stack 310 increases faster than the temperature of second battery stack 320. In addition, during the time period in which the circuit 330 operates in the first switching mode, the second battery pack 320 may be charged and the first battery pack 310 may consume power. In this manner, during the time period in which the circuit 330 is operating in the first switching mode, a temperature and charge imbalance may develop between the battery packs 310, 320. To correct for this imbalance, the circuit 330 may switch to the second switching mode.
A controller (e.g., control circuitry 140) may turn switching element 332C on and switching element 332D off to transition circuitry 330 to the second switching mode. In some examples, circuitry 330 is configured to draw a third current from second battery pack 320 using switching element 332B when switching element 332B is on. For example, when switching element 332B is turned on, switching element 332B generates a short circuit between the positive terminal and the negative terminal of second battery stack 320, thereby inducing a current across second battery stack 320 and switching element 332B. As current flows through the physical structure of second battery pack 320 and, in turn, through second internal resistance 324, second battery pack 320 dissipates heat due to the joule effect. Thus, the third current induced by switching element 332B increases the temperature of second battery pack 320.
The second battery pack 320 is configured to emit a second overcurrent after the switching element 332B is turned off. Circuit 330 is configured to deliver at least some of the second overcurrent to first battery pack 310 when switching element 332B is off. In addition, the circuit 330 may use at least some of the second overcurrent to charge the capacitor 334. The inductive characteristic of second battery pack 320 (e.g., second internal inductance 322) may cause second battery pack 320 to emit a second overcurrent. In the example shown in fig. 3, second battery pack 320 discharges a second overcurrent to the positive terminal of first battery pack 310 through diode 338 and switching element 332C. The second overcurrent flows from the positive terminal to the negative terminal through the first cell stack 310. Since the second overcurrent passes through the first internal resistance 314, the first battery pack 310 may emit heat. Therefore, the second overcurrent may recharge the first battery pack 310, and the second overcurrent may increase the temperature of the first battery pack 310.
In some cases, after the capacitor 334 is charged with the second overcurrent, the switching element 332B is turned on. After switching element 332B is turned on, capacitor 334 discharges, releasing the fourth current to second battery stack 310 via switching element 332C.
During the second switching mode, the circuit 330 may operate in two phases. During the first phase, switching element 332B is turned on, so that the third current flows through second battery stack 320 and switching element 332B, and the fourth current flows from discharge capacitor 334 to first battery stack 310 through switching element 332C. During the second phase, the switching element 332B is turned off and the second battery pack 320 emits the second overcurrent. The circuit 330 may use at least some of the second overcurrent to charge the capacitor 334. In addition, circuit 330 delivers at least some of the second overcurrent to first battery pack 310 via diode 338 and switching element 332C. In some examples, the fourth current and the second overcurrent flow from the positive terminal to the negative terminal through the first battery stack 310.
To balance the temperature and charge of the battery packs 310, 320 during the battery heating process of the system 300, a controller (e.g., the control circuit 140 of fig. 1) may alternate the circuit 330 between the first switching mode and the second switching mode according to one or more techniques that will be described in further detail below. To alternate between the first switching mode and the second switching mode, the controller delivers an electrical signal to the control terminal of the switching element 332, configuring the circuit 330 to operate in the respective switching mode.
In some examples, the circuit 330 is configured to operate in a first switching mode during a plurality of primary stages, wherein each primary stage of the plurality of primary stages lasts a first amount of time. Additionally, the circuit 330 is configured to operate in a second switching mode during a plurality of secondary phases, wherein each secondary phase of the plurality of secondary phases lasts for a second amount of time. The circuit 330 may interleave the plurality of primary stages and the plurality of secondary stages such that a primary stage is followed by a secondary stage and a secondary stage is followed by a successive primary stage. In other words, the circuit 330 may alternate between the first switching mode and the second switching mode at predetermined time intervals. In some examples, the first amount of time is equal to the second amount of time. In some examples, the first amount of time and the second amount of time are greater than one minute and less than five minutes.
In some examples, a first temperature sensor (not shown in fig. 3) is configured to measure a temperature of first battery pack 310, and a second temperature sensor (not shown in fig. 3) is configured to measure a temperature of second battery pack 320. Based on the measured temperatures of battery packs 310, 320, the controller may change circuit 330 from operating in the first switching mode to operating in the second switching mode if the temperature of first battery pack 310 is greater than the temperature of second battery pack 320 by a temperature difference threshold. Additionally, if the temperature of second battery pack 320 is greater than the temperature of first battery pack 310 by more than the temperature difference threshold, the controller may change circuit 330 from operating in the second switching mode to operating in the first switching mode. In some examples, the temperature difference threshold is greater than 1 degree celsius and less than 5 degrees celsius. However, in other examples, other temperature difference thresholds may be used. The temperature difference threshold may be any temperature value or range of temperature values.
In some examples, a first voltage sensor (not shown in fig. 3) is configured to measure a magnitude of the voltage of first battery stack 310, and a second voltage sensor (not shown in fig. 3) is configured to measure a magnitude of the voltage of second battery stack 320. The controller is configured to change the circuit 330 from operating in the first switching mode to operating in the second switching mode if the magnitude of the voltage of the first battery stack 310 is less than the magnitude of the voltage of the second battery stack 320 by more than the voltage difference threshold. Additionally, the controller is configured to change the circuit 330 from operating in the second switching mode to operating in the first switching mode if the magnitude of the voltage of the second battery pack 320 is less than the magnitude of the voltage of the first battery pack 310 by more than the voltage difference threshold. In some examples, the voltage difference threshold is greater than 5 volts and less than 20 volts. However, in other examples, other voltage level difference thresholds may be used.
Fig. 4 is a circuit diagram of a system 400 including a first battery pack 410, a second battery pack 420, a circuit 430, a load 450, according to one or more techniques of the present disclosure. First battery pack 410 includes a first internal inductor 412, a first internal resistor 414, and a first power source 416. Second battery pack 420 includes a second internal inductor 422, a second internal resistor 424, and a second power source 426. The circuit 430 includes switching elements 432A to 432D (collectively referred to as "switching elements 432") and a capacitor 434. First battery pack 410 may be an example of first battery pack 110 of fig. 1. Second battery stack 420 may be an example of second battery stack 120 of fig. 1. The circuit 430 may be an example of the circuit 130 of fig. 1. Load 450 may be an example of load 150 of fig. 1.
In some cases, circuitry 430 may perform a battery heating process to increase the temperature of first battery pack 410 and second battery pack 420 (collectively, "battery packs 410, 420"). For example, a controller (e.g., control circuit 140 of fig. 1) may be configured to control switching element 432 of circuit 430 to alternate between a first switching mode and a second switching mode. During both the first switching mode and the second switching mode, the switching element 432C and the switching element 432D may be turned on. The switching element 432 may be an example of the switching element 132 of fig. 1. In some examples, switching elements 432A and 432B may include any combination of silicon MOSFETs, silicon JFETs, superjunction MOSFETs, gallium nitride HEMTs, gallium nitride MOSFETs, silicon carbide MOSFETs, or silicon carbide JFETs. In some examples, switching elements 432C and 432D are slow switching devices, such as electromechanical-based switching devices (e.g., relays). In some examples, each of switching elements 432C and 432D includes a body diode.
During the first switching mode, the circuit 430 may operate in two phases. During the first phase, switching element 432A is turned on, so that a first current flows through first battery stack 410 and switching element 432A, and a second current flows from discharge capacitor 434 to second battery stack 420 through switching element 432D. During the second phase, the switching element 432A is turned off and the first battery pack 410 emits the first overcurrent. The circuit 430 may use at least some of the first overcurrent to charge the capacitor 434. In addition, circuit 430 delivers at least some of the first overcurrent to second battery pack 420 via switching element 432D. In some examples, the second current and the first overcurrent flow from the positive terminal to the negative terminal through the second battery pack 420.
During the second switching mode, the circuit 430 may operate in two phases. During the first phase, switching element 432B is turned on, so that a third current flows through second battery pack 420 and switching element 432B, and a fourth current flows from discharge capacitor 434 to first battery pack 410 through switching element 432C. During the second phase, switching element 432B is turned off and second battery pack 420 emits the second overcurrent. The circuit 430 may use at least some of the second overcurrent to charge the capacitor 434. In addition, circuit 430 delivers at least some of the second overcurrent to first battery pack 410 via switching elements 432C and 432D. In some examples, the fourth current and the second overcurrent flow from the positive terminal to the negative terminal through the first battery pack 410.
Based on data from any combination of temperature sensors and voltage sensors, circuit 430 may alternate between a first switching mode and a second switching mode to balance the temperature and charge level of battery packs 410, 420. While performing the battery warm-up process, the circuit 430 may avoid delivering power to the load 450.
After the temperature of the battery packs 410, 420 increases above the temperature threshold, the battery warm-up process may end. Circuit 430 may then connect any combination of battery packs 410, 420 to load 450. For example, circuit 430 may deliver current from first battery pack 410 to load 450 via switching element 432C, and circuit 430 may deliver current from second battery pack 420 to load 450 via switching element 432D. At any time, circuit 430 may disconnect load 450 from first battery pack 410 by turning off switching element 432C. In addition, at any time, circuit 430 may disconnect second battery pack 420 from load 450 by turning off switching element 432D.
Fig. 5 is a flow diagram illustrating an example technique for heating a first battery pack and a second battery pack using a circuit in accordance with one or more techniques of the present disclosure. The technique of fig. 5 is described with respect to the controller 100 shown in fig. 1, although other systems, such as the systems 200, 300, and 400 shown in fig. 2-4, may illustrate similar techniques.
In the example of fig. 5, circuitry 130 is configured to draw current from first battery stack 110 using the switching element (510) when the switching element of one or more switching elements 132 is turned on. By turning on the switching element, circuit 130 may create a short circuit between the positive and negative terminals of first battery stack 110, thereby inducing a first current through first battery stack 110. The physical structure of first battery stack 110 may define a resistance value such that the physical structure of first battery stack 110 releases heat when a first current flows through first battery stack 110. The release of heat from first battery stack 110 causes the temperature of first battery stack 110 to increase. In addition, when the switching element draws the first current from the first battery stack 110, the charge level of the first battery stack 110 decreases. In other words, the first current may represent a consumption of at least some of the power stored by first battery stack 110.
When the switching element is turned off, circuit 130 may be configured to deliver at least some of the overcurrent to second battery stack 120, which is issued by first battery stack 110 (520). The internal inductance of first battery stack 110, which resists the change from the first current through first battery stack 110, may cause first battery stack 110 to emit an overcurrent. Circuit 130 may deliver an overcurrent to second battery stack 120 such that the overcurrent passes through the internal resistance of second battery stack 120, causing second battery stack 120 to heat. Additionally, the circuit 130 may include a capacitor. When the switching element is turned off, the circuit 130 charges the capacitor with the overcurrent (530). When the switching element is turned on, circuit 130 causes the capacitor to discharge, which sends a second current to second battery stack 120 (540). As with the overcurrent, the second current may cause second battery pack 120 to heat. The overcurrent and the second current may pass through the second battery pack 120 from the positive terminal to the negative terminal such that the overcurrent and the second current recharge the second battery pack 120. The example of fig. 5 may result in first battery stack 110 heating up faster than second battery stack 120, and the example of fig. 5 may also cause first battery stack 110 to lose charge and second battery stack 120 to gain charge.
Although the example of fig. 5 depicts a system in which first battery stack 110 heats up faster than second battery stack 120, some of the techniques described with respect to fig. 5 may be applied to heat up second battery stack 120 faster than first battery stack 110. For example, a multi-directional battery heating circuit (e.g., circuit 330 of fig. 3) may balance the rate of heating of two battery packs.
The following numbered examples illustrate one or more aspects of the present disclosure.
Example 1. a circuit comprising a switching element. The circuit is configured to draw current from a first battery pack using the switching element when the switching element is on, the first battery pack emitting an overcurrent after the switching element is off, wherein the current causes a temperature of the first battery pack to increase, and to deliver at least some of the overcurrent to a second battery pack when the switching element is off, wherein the overcurrent charges the second battery pack, and wherein the overcurrent causes a temperature of the second battery pack to increase.
Example 2 the circuit of example 1, wherein the current increases the temperature of the first battery pack by passing through a resistance of the first battery pack, and wherein the over-current increases the temperature of the second battery pack by passing through a resistance of the second battery pack.
Example 3 the circuit of examples 1-2, or any combination thereof, wherein the current comprises a first current, wherein the circuit further comprises a capacitor, and wherein the circuit is further configured to charge the capacitor with the overcurrent when the switching element is off, and to discharge the capacitor when the switching element is on, the capacitor sourcing a second current to the second battery pack, wherein the second current charges the second battery pack, and wherein the second current increases a temperature of the second battery pack.
Example 4 the circuit of examples 1-3, or any combination thereof, wherein the switching element comprises a first switching element, wherein the circuit further comprises a second switching element, and wherein the circuit is further configured to operate in a first switching mode and operate in a second switching mode, wherein, operating in the first switching mode, the circuit is configured to charge the second battery pack using the overcurrent and the second current when the second switching element is off, and wherein, operating in the second switching mode, the circuit is configured to charge the first battery pack when the first switching element is off.
Example 5 the circuit of examples 1-4, or any combination thereof, wherein the overcurrent comprises a first overcurrent. Operating in the second switching mode, the circuitry configured to draw a third current from the second battery pack when the second switching element is on, the second battery pack sourcing a second overcurrent after the second switching element is off, and deliver at least some of the second overcurrent to the first battery pack when the second switching element is off. Further, the circuit is configured such that, when the second switching element is turned off, the capacitor is charged with the second overcurrent, and when the second switching element is turned on, the capacitor is discharged, the capacitor issues a fourth current to the first battery pack, wherein the third current increases the temperature of the second battery pack, wherein the second overcurrent increases the temperature of the first battery pack, and wherein the fourth current increases the temperature of the first battery pack.
Example 6 the circuit of examples 1-5, or any combination thereof, wherein the circuit further comprises a third switching element, a fourth switching element, a first diode, and a second diode. Operating in the first switching mode, the circuit being further configured to deliver at least some of the first overcurrent to the second battery pack via the first diode when the third switching element is off and the fourth switching element is on. Additionally, operating in the second switching mode, the circuit is further configured to deliver at least some of the second overcurrent to the first battery pack via the second diode when the third switching element is turned on and the fourth switching element is turned off.
Example 7 the circuit of examples 1-6, or any combination thereof, wherein the circuit further comprises a third switching element and a fourth switching element. The circuit is further configured to connect a load to the first battery pack and the second battery pack when the third switching element is on and the fourth switching element is on, disconnect the load from the first battery pack when the third switching element is off, and disconnect the load from the second battery pack when the fourth switching element is off.
Example 8 the circuit of examples 1-7, or any combination thereof, wherein the first switching element, the second switching element, the third switching element, and the fourth switching element each comprise a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), an Insulated Gate Bipolar Transistor (IGBT), or a Junction Field Effect Transistor (JFET).
Example 9 the circuit of examples 1-8, or any combination thereof, wherein the circuit is configured to operate in the first switching mode during a plurality of primary stages, wherein each of the plurality of primary stages lasts a first amount of time, operate in the second switching mode during a plurality of secondary stages, wherein each of the plurality of secondary stages lasts a second amount of time, and interleave the plurality of primary stages and the plurality of secondary stages such that a primary stage is followed by a secondary stage and the secondary stage is followed by a successive primary stage.
Example 10 the circuit of examples 1-9, or any combination thereof, wherein the circuit is further configured to change from operating in the first switching mode to operating in the second switching mode if the temperature of the first battery pack is greater than the temperature of the second battery pack by a temperature difference threshold, and to change from operating in the second switching mode to operating in the first switching mode if the temperature of the second battery pack is greater than the temperature of the first battery pack by the temperature difference threshold.
Example 11 the circuit of examples 1-10, wherein the circuit is further configured to change from operating in the first switching mode to operating in the second switching mode if the magnitude of the voltage of the first battery pack is less than the magnitude of the voltage of the second battery pack by more than a voltage difference threshold, and to change from operating in the second switching mode to operating in the first switching mode if the magnitude of the voltage of the second battery pack is less than the magnitude of the voltage of the first battery pack by more than the voltage difference threshold.
Example 12. a system, comprising: a first battery pack including a first positive terminal and a first negative terminal; a second battery pack comprising a second positive terminal and a second negative terminal, wherein the second battery pack is connected in parallel with the first battery pack. Additionally, the system includes a circuit. The circuit comprises: a switching element including a source terminal and a drain terminal, wherein the switching element is connected in parallel with the first battery pack and the second battery pack, wherein the source terminal is electrically connected to the first negative terminal and the drain terminal is electrically connected to the first positive terminal, and wherein the first positive terminal and the second negative terminal are electrically connected via the switching element when the switching element is turned on.
Example 13 the system of example 12, wherein the circuit further comprises a capacitor connected in parallel with the switching element.
Example 14 the system of examples 12-13, or any combination thereof, wherein the circuit further comprises a diode comprising a cathode and an anode, wherein the cathode is electrically coupled to the capacitor and the second positive terminal, and wherein the anode is electrically coupled to the first positive terminal.
Example 15 the system of examples 12-14, or any combination thereof, wherein the switching element comprises a first switching element, wherein the source terminal comprises a first source terminal, and wherein the drain terminal comprises a first drain terminal. The circuit further includes a second switching element including a second source terminal and a second drain terminal, the second switching element being connected in parallel with the capacitor and the first switching element, wherein the second source terminal is electrically connected to the second negative terminal, wherein the second drain terminal is electrically connected to the second positive terminal, and wherein the first positive terminal and the second negative terminal are electrically connected via the second switching element when the second switching element is turned on.
Example 16. the system of examples 12-15, wherein the circuit further includes a third switching element, a fourth switching element, a first diode, and a second diode, the first diode including a first cathode and a first anode, the second diode including a second cathode and a second anode, wherein the third switching element is electrically connected to the first positive terminal of the first battery pack and the third switching element is electrically connected to the second positive terminal of the second battery pack via the second diode, wherein the fourth switching element is electrically connected to the second positive terminal and the fourth switching element is electrically connected to the first positive terminal via the first diode, wherein the first anode of the first diode is electrically connected to the first positive terminal and the first cathode is electrically connected to the capacitor, and wherein the second anode of the second diode is electrically connected to the second positive terminal and the second cathode is electrically connected to the capacitor.
Example 17. the system of examples 12-16, wherein the circuit further includes a third switching element electrically connected to the first positive terminal of the first battery pack and a fourth switching element electrically connected to the second positive terminal of the second battery pack. In addition, the system further includes a load electrically connected to the third switching element and the fourth switching element.
Example 18 the system of examples 12-17, wherein the first, second, third, and fourth switching elements each comprise a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), an Insulated Gate Bipolar Transistor (IGBT), or a Junction Field Effect Transistor (JFET).
Example 19 the system of examples 12-18, further comprising one or more sensors, wherein the circuitry is configured to activate and deactivate the first, second, third, and fourth switching elements based on the one or more sensors.
Example 20. a method, comprising: drawing a current from a first battery pack using a switching element of a circuit when the switching element is turned on, wherein the current increases a temperature of the first battery pack; and when the switching element is off, delivering at least some of an overcurrent to a second battery pack using the circuit, wherein the overcurrent is issued by the first battery pack, wherein the overcurrent charges the second battery pack, and wherein the overcurrent increases a temperature of the second battery pack.
Various examples of the present disclosure have been described. These and other examples are within the scope of the following claims.

Claims (20)

1. A circuit for inducing current, the circuit comprising a switching element, wherein the circuit is configured to:
drawing a current from a first battery pack using the switching element when the switching element is turned on, the first battery pack emitting an overcurrent after the switching element is turned off,
wherein the current increases a temperature of the first battery pack; and
delivering at least some of the over-current to a second battery pack when the switching element is off, wherein the over-current charges the second battery pack, and wherein the over-current increases a temperature of the second battery pack.
2. The circuit of claim 1, wherein the current increases the temperature of the first battery pack by passing through a resistance of the first battery pack, and wherein the over-current increases the temperature of the second battery pack by passing through a resistance of the second battery pack.
3. The circuit of claim 1, wherein the current comprises a first current, wherein the circuit further comprises a capacitor, and wherein the circuit is further configured to:
charging the capacitor with the overcurrent when the switching element is turned off; and
discharging the capacitor when the switching element is turned on, the capacitor emitting a second current to the second battery pack, wherein the second current charges the second battery pack, and wherein the second current increases a temperature of the second battery pack.
4. The circuit of claim 3, wherein the switching element comprises a first switching element, wherein the circuit further comprises a second switching element, and wherein the circuit is further configured to operate in a first switching mode and to operate in a second switching mode,
wherein operating in the first switching mode, the circuit is configured to charge the second battery pack with the overcurrent and the second current when the second switching element is turned off, and
wherein operating in the second switching mode, the circuit is configured to charge the first battery pack when the first switching element is off.
5. The circuit of claim 4, wherein the overcurrent comprises a first overcurrent, and wherein, operating in the second switching mode, the circuit is configured to:
drawing a third current from the second battery pack when the second switching element is turned on, the second battery pack issuing a second overcurrent after the second switching element is turned off,
delivering at least some of the second overcurrent to the first battery pack when the second switching element is turned off;
charging the capacitor with the second overcurrent when the second switching element is turned off, an
Discharging the capacitor when the second switching element is turned on, the capacitor emitting a fourth current to the first battery pack,
wherein the third current increases the temperature of the second battery pack, wherein the second overcurrent increases the temperature of the first battery pack, and wherein the fourth current increases the temperature of the first battery pack.
6. The circuit of claim 5, wherein the circuit further comprises a third switching element, a fourth switching element, a first diode, and a second diode, and wherein, operating in the first switching mode, the circuit is further configured to:
delivering at least some of the first overcurrent to the second battery bank via the first diode when the third switching element is turned off and the fourth switching element is turned on,
wherein operating in the second switching mode, the circuit is further configured to:
delivering at least some of the second overcurrent to the first battery pack via the second diode when the third switching element is turned on and the fourth switching element is turned off.
7. The circuit of claim 5, wherein the circuit further comprises a third switching element and a fourth switching element, and wherein the circuit is further configured to:
connecting a load to the first battery pack and the second battery pack when the third switching element is turned on and the fourth switching element is turned on;
disconnecting the load from the first battery pack when the third switching element is turned off; and
disconnecting the load from the second battery pack when the fourth switching element is turned off.
8. The circuit of claim 7, wherein the first switching element, the second switching element, the third switching element, and the fourth switching element each comprise a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), an Insulated Gate Bipolar Transistor (IGBT), or a Junction Field Effect Transistor (JFET).
9. The circuit of claim 4, wherein the circuit is configured to:
operating in the first switching mode during a plurality of primary phases, wherein each primary phase of the plurality of primary phases lasts for a first amount of time;
operating in the second switching mode during a plurality of secondary phases, wherein each secondary phase of the plurality of secondary phases lasts a second amount of time; and
the plurality of primary stages and the plurality of secondary stages are interleaved such that one primary stage is followed by one secondary stage and the secondary stage is followed by the next primary stage.
10. The circuit of claim 4, wherein the circuit is further configured to:
changing from operating in the first switching mode to operating in the second switching mode if the temperature of the first battery pack is greater than the temperature of the second battery pack by a temperature difference threshold; and
changing from operating in the second switching mode to operating in the first switching mode if the temperature of the second battery pack is greater than the temperature of the first battery pack by more than the temperature differential threshold.
11. The circuit of claim 4, wherein the circuit is further configured to:
changing from operating in the first switching mode to operating in the second switching mode if the magnitude of the voltage of the first battery pack is less than the magnitude of the voltage of the second battery pack by more than a voltage difference threshold; and
changing from operating in the second switching mode to operating in the first switching mode if the magnitude of the voltage of the second battery pack is less than the magnitude of the voltage of the first battery pack by more than the voltage difference threshold.
12. A system for inducing current, comprising:
a first battery pack including a first positive terminal and a first negative terminal;
a second battery pack comprising a second positive terminal and a second negative terminal, wherein the second battery pack is connected in parallel with the first battery pack; and
a circuit, the circuit comprising:
a switching element including a source terminal and a drain terminal, wherein the switching element is connected in parallel with the first battery pack and the second battery pack, wherein the source terminal is electrically connected to the first negative terminal and the drain terminal is electrically connected to the first positive terminal, and wherein the first positive terminal and the second negative terminal are electrically connected via the switching element when the switching element is turned on.
13. The system of claim 12, wherein the circuit further comprises a capacitor connected in parallel with the switching element.
14. The system of claim 13, wherein the circuit further comprises a diode comprising a cathode and an anode, wherein the cathode is electrically coupled to the capacitor and the second positive terminal, and wherein the anode is electrically coupled to the first positive terminal.
15. The system of claim 13, wherein the switching element comprises a first switching element, wherein the source terminal comprises a first source terminal, wherein the drain terminal comprises a first drain terminal, and wherein the circuit further comprises:
a second switching element including a second source terminal and a second drain terminal, the second switching element being connected in parallel with the capacitor and the first switching element,
wherein the second source terminal is electrically connected to the second negative terminal,
wherein the second drain terminal is electrically connected to the second positive terminal, an
Wherein when the second switching element is turned on, the first positive terminal and the second negative terminal are electrically connected via the second switching element.
16. The system of claim 15, wherein the circuitry further comprises:
a third switching element;
a fourth switching element;
a first diode comprising a first cathode and a first anode; and
a second diode comprising a second cathode and a second anode,
wherein the third switching element is electrically connected to the first positive terminal of the first battery pack, and the third switching element is electrically connected to the second positive terminal of the second battery pack via the second diode,
wherein the fourth switching element is electrically connected to the second positive terminal, and the fourth switching element is electrically connected to the first positive terminal via the first diode,
wherein the first anode of the first diode is electrically connected to the first positive terminal and the first cathode is electrically connected to the capacitor, an
Wherein the second anode of the second diode is electrically connected to the second positive terminal and the second cathode is electrically connected to the capacitor.
17. The system of claim 15, wherein the circuitry further comprises:
a third switching element electrically connected to the first positive terminal of the first battery pack; and
a fourth switching element electrically connected to the second positive terminal of the second battery pack, wherein the system further comprises:
a load electrically connected to the third switching element and the fourth switching element.
18. The system of claim 17, wherein the first switching element, the second switching element, the third switching element, and the fourth switching element each comprise a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), an Insulated Gate Bipolar Transistor (IGBT), or a Junction Field Effect Transistor (JFET).
19. The system of claim 16, further comprising one or more sensors, wherein the circuit is configured to activate and deactivate the first, second, third, and fourth switching elements based on the one or more sensors.
20. A method for inducing current, comprising:
drawing current from the first battery pack with a switching element of the circuit when the switching element is turned on,
wherein the current increases a temperature of the first battery pack; and
delivering, with the circuit, at least some of an overcurrent to a second battery pack when the switching element is turned off, wherein the overcurrent is issued by the first battery pack, wherein the overcurrent charges the second battery pack, and wherein the overcurrent increases a temperature of the second battery pack.
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